Simplify FontHandle and rename it to PlatformFont (#32101)

* Simplify `FontHandle` and rename it to `PlatformFont`

Rename it to `PlatformFont` and move the `FontTemplate` member to
`Font`, because it's shared by all platforms.

* Update components/gfx/platform/freetype/font.rs

Co-authored-by: Mukilan Thiyagarajan <mukilanthiagarajan@gmail.com>

* Fix build for MacOS and Windows

---------

Co-authored-by: Mukilan Thiyagarajan <mukilanthiagarajan@gmail.com>

components/gfx/platform/freetype/font.rs

@@ -4,6 +4,7 @@
 
 use std::ffi::CString;
 use std::os::raw::{c_char, c_long};
+use std::sync::Arc;
 use std::{mem, ptr};
 
 use app_units::Au;
@@ -23,7 +24,7 @@ use style::values::computed::font::FontStyle;
 use super::c_str_to_string;
 use super::library_handle::FreeTypeLibraryHandle;
 use crate::font::{
-    FontHandleMethods, FontMetrics, FontTableMethods, FontTableTag, FractionalPixel, GPOS, GSUB,
+    FontMetrics, FontTableMethods, FontTableTag, FractionalPixel, PlatformFontMethods, GPOS, GSUB,
     KERN,
 };
 use crate::font_cache_thread::FontIdentifier;
@@ -70,15 +71,18 @@ struct OS2Table {
 
 #[derive(Debug)]
 #[allow(unused)]
-pub struct FontHandle {
-    // The template contains the font data, which must stay valid for the
-    // lifetime of the platform [`FT_Face`], if it's created via [`FT_Memory_Face`].
-    font_template: FontTemplateRef,
+pub struct PlatformFont {
+    /// The font data itself, which must stay valid for the lifetime of the
+    /// platform [`FT_Face`], if it's created via [`FT_New_Memory_Face`]. A reference
+    /// to this data is also stored in the [`crate::font::Font`] that holds
+    /// this [`PlatformFont`], but if it's ever separated from it's font,
+    /// this ensures the data stays alive.
+    font_data: Option<Arc<Vec<u8>>>,
     face: FT_Face,
     can_do_fast_shaping: bool,
 }
 
-impl Drop for FontHandle {
+impl Drop for PlatformFont {
     fn drop(&mut self) {
         assert!(!self.face.is_null());
         unsafe {
@@ -134,22 +138,22 @@ fn create_face(template: &FontTemplateRef, pt_size: Option<Au>) -> Result<FT_Fac
         }
 
         if let Some(s) = pt_size {
-            FontHandle::set_char_size(face, s)?
+            PlatformFont::set_char_size(face, s)?
         }
 
         Ok(face)
     }
 }
 
-impl FontHandleMethods for FontHandle {
+impl PlatformFontMethods for PlatformFont {
     fn new_from_template(
         template: FontTemplateRef,
         pt_size: Option<Au>,
-    ) -> Result<FontHandle, &'static str> {
+    ) -> Result<PlatformFont, &'static str> {
         let face = create_face(&template, pt_size)?;
-        let mut handle = FontHandle {
+        let mut handle = PlatformFont {
             face,
-            font_template: template.clone(),
+            font_data: template.borrow().data_if_in_memory(),
             can_do_fast_shaping: false,
         };
         // TODO (#11310): Implement basic support for GPOS and GSUB.
@@ -158,10 +162,6 @@ impl FontHandleMethods for FontHandle {
         Ok(handle)
     }
 
-    fn template(&self) -> FontTemplateRef {
-        self.font_template.clone()
-    }
-
     fn family_name(&self) -> Option<String> {
         unsafe {
             let family_name = (*self.face).family_name;
@@ -362,7 +362,7 @@ impl FontHandleMethods for FontHandle {
     }
 }
 
-impl<'a> FontHandle {
+impl<'a> PlatformFont {
     fn set_char_size(face: FT_Face, pt_size: Au) -> Result<(), &'static str> {
         let char_size = pt_size.to_f64_px() * 64.0 + 0.5;
 

components/gfx/platform/macos/font.rs

@@ -4,6 +4,7 @@
 
 use std::cmp::Ordering;
 use std::ops::Range;
+use std::sync::Arc;
 use std::{fmt, ptr};
 
 /// Implementation of Quartz (CoreGraphics) fonts.
@@ -22,7 +23,7 @@ use style::values::computed::font::{FontStretch, FontStyle, FontWeight};
 
 use super::font_template::CoreTextFontTemplateMethods;
 use crate::font::{
-    FontHandleMethods, FontMetrics, FontTableMethods, FontTableTag, FractionalPixel, GPOS, GSUB,
+    FontMetrics, FontTableMethods, FontTableTag, FractionalPixel, PlatformFontMethods, GPOS, GSUB,
     KERN,
 };
 use crate::font_template::FontTemplateRef;
@@ -52,14 +53,16 @@ impl FontTableMethods for FontTable {
 }
 
 #[derive(Debug)]
-pub struct FontHandle {
-    font_template: FontTemplateRef,
+pub struct PlatformFont {
     ctfont: CTFont,
+    /// A reference to this data used to create this [`PlatformFont`], ensuring the
+    /// data stays alive of the lifetime of this struct.
+    _data: Option<Arc<Vec<u8>>>,
     h_kern_subtable: Option<CachedKernTable>,
     can_do_fast_shaping: bool,
 }
 
-impl FontHandle {
+impl PlatformFont {
     /// Cache all the data needed for basic horizontal kerning. This is used only as a fallback or
     /// fast path (when the GPOS table is missing or unnecessary) so it needn't handle every case.
     fn find_h_kern_subtable(&self) -> Option<CachedKernTable> {
@@ -154,11 +157,11 @@ impl fmt::Debug for CachedKernTable {
     }
 }
 
-impl FontHandleMethods for FontHandle {
+impl PlatformFontMethods for PlatformFont {
     fn new_from_template(
         font_template: FontTemplateRef,
         pt_size: Option<Au>,
-    ) -> Result<FontHandle, &'static str> {
+    ) -> Result<PlatformFont, &'static str> {
         let size = match pt_size {
             Some(s) => s.to_f64_px(),
             None => 0.0,
@@ -167,8 +170,8 @@ impl FontHandleMethods for FontHandle {
             return Err("Could not generate CTFont for FontTemplateData");
         };
 
-        let mut handle = FontHandle {
-            font_template,
+        let mut handle = PlatformFont {
+            _data: font_template.borrow().data_if_in_memory(),
             ctfont: core_text_font.clone_with_font_size(size),
             h_kern_subtable: None,
             can_do_fast_shaping: false,
@@ -181,10 +184,6 @@ impl FontHandleMethods for FontHandle {
         Ok(handle)
     }
 
-    fn template(&self) -> FontTemplateRef {
-        self.font_template.clone()
-    }
-
     fn family_name(&self) -> Option<String> {
         Some(self.ctfont.family_name())
     }

components/gfx/platform/windows/font.rs

@@ -8,6 +8,7 @@
 
 use std::fmt;
 use std::ops::Deref;
+use std::sync::Arc;
 
 use app_units::Au;
 use dwrote::{Font, FontFace, FontFile, FontStretch, FontStyle};
@@ -18,7 +19,7 @@ use style::values::computed::font::FontStyle as StyleFontStyle;
 use style::values::specified::font::FontStretchKeyword;
 
 use crate::font::{
-    FontHandleMethods, FontMetrics, FontTableMethods, FontTableTag, FractionalPixel,
+    FontMetrics, FontTableMethods, FontTableTag, FractionalPixel, PlatformFontMethods,
 };
 use crate::font_cache_thread::FontIdentifier;
 use crate::font_template::{FontTemplateRef, FontTemplateRefMethods};
@@ -198,9 +199,11 @@ impl FontInfo {
 }
 
 #[derive(Debug)]
-pub struct FontHandle {
-    font_template: FontTemplateRef,
+pub struct PlatformFont {
     face: Nondebug<FontFace>,
+    /// A reference to this data used to create this [`PlatformFont`], ensuring the
+    /// data stays alive of the lifetime of this struct.
+    data: Option<Arc<Vec<u8>>>,
     info: FontInfo,
     em_size: f32,
     du_to_px: f32,
@@ -222,9 +225,7 @@ impl<T> Deref for Nondebug<T> {
     }
 }
 
-impl FontHandle {}
-
-impl FontHandleMethods for FontHandle {
+impl PlatformFontMethods for PlatformFont {
     fn new_from_template(
         font_template: FontTemplateRef,
         pt_size: Option<Au>,
@@ -234,8 +235,12 @@ impl FontHandleMethods for FontHandle {
             FontIdentifier::Web(_) => None,
         };
 
-        let (face, info) = match direct_write_font {
-            Some(font) => (font.create_font_face(), FontInfo::new_from_font(&font)?),
+        let (face, info, data) = match direct_write_font {
+            Some(font) => (
+                font.create_font_face(),
+                FontInfo::new_from_font(&font)?,
+                None,
+            ),
             None => {
                 let bytes = font_template.data();
                 let font_file =
@@ -244,7 +249,7 @@ impl FontHandleMethods for FontHandle {
                     .create_face(0, dwrote::DWRITE_FONT_SIMULATIONS_NONE)
                     .map_err(|_| "Could not create FontFace")?;
                 let info = FontInfo::new_from_face(&face)?;
-                (face, info)
+                (face, info, font_template.borrow().data_if_in_memory())
             },
         };
 
@@ -257,9 +262,9 @@ impl FontHandleMethods for FontHandle {
         let design_units_to_pixels = 1. / design_units_per_pixel;
         let scaled_design_units_to_pixels = em_size / design_units_per_pixel;
 
-        Ok(FontHandle {
-            font_template,
+        Ok(PlatformFont {
             face: Nondebug(face),
+            data,
             info,
             em_size,
             du_to_px: design_units_to_pixels,
@@ -267,10 +272,6 @@ impl FontHandleMethods for FontHandle {
         })
     }
 
-    fn template(&self) -> FontTemplateRef {
-        self.font_template.clone()
-    }
-
     fn family_name(&self) -> Option<String> {
         Some(self.info.family_name.clone())
     }